This invention relates to a double ended ranging drum shearer (hereinafter referred to simply as "shearer") used for a long-wall mining having a working height controller capable of automatically controlling the elevating movement of cutting drums provided for the shearer to thereby keep constant the working height at a mining face, and relates to a method of controlling the working height to be constant in use of the double ranging shearer of the character described above.
With a conventional long wall mining plant, two operators are generally required for operating a double ranging shearer, one for manipulating the front drum and observing the cutting condition and speed of the shearer in a front, i.e., advancing, direction and the other for manipulating the rear drum and observing the cutting and loading condition of the rear drum at the rear portion, and much experience and expert skill are required for these observations and manipulating. The mining working is usually carried out by adjusting or regulating the drum height and shearer speed in accordance with the roof and floor conditions in a mining pit which vary intricately.
Although it may be possible for one operator to control the shearer under good conditions of a mining pit wherein a mining face such as a coal face is substantially straight and a coal seam has a constant thickness, in such a case, the rear side drum is not usually operated and is maintained at an appropriate position between the roof and the floor of the mining face.
As described hereinabove, in the conventional mining working in use of a shearer, two skilled operators have to be disposed at the front and rear portions of the cutter, and the two operators have paid attention to a coincidence of their operation timings for mining the coal face while properly maintaining the constant working height.
The following two managing items are deemed to be most important ones in the working of the mining face:
(a) to keep the mining face straight; and
(b) to keep the working height as constant as possible so as to make easy the operation and management of shield supports to hold the roof of the mining face.
The item (a) is managed by an operator who manages the shield supports and the item (b) is managed by an operator who operates the shearer.
The operators should always pay attention to the mutual relationship in height of the front and rear drums of the shearer because the working height at the mining face is determined by the respective heights of these drums. The determination of the working height may be relatively easily done in a case where the floor (or roof) of the mining pit is flat or straight, but in usual, the floor (or roof) is not flat and uneven, and the shearer has a whole length of about 8-10 m, so that it is substantially impossible to keep constant the working height even in the simultaneous operations of both the front and rear drums. Taking the above fact into consideration, it is necessary for the operator who handles the rear drum to always pay attention to the roof condition or height to adjust the working height to be as constant as possible.
Recently, however, on the basis of the improvement of the working condition and the environmental sanitation in the mining pit, a radio controlling unit has been equipped for the shearer thereby to remotely control the same by one operator at a windward position without being exposed to dust and dirt.
In this remotely controlled operation, although the height and the cutting condition of the front drum can be adequately observed and managed, the observation and management of the rear drum can hardly be done because the rear drum is separated by more than about 10 m from the operator. Accordingly, this remote control operation can possibly be applied only to a mining face in which the coal seam of the coal face is relatively straight and cannot be applied to any mining face exposing various floor conditions.